Brake Pads

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IanB
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Brake Pads

Post by IanB »

I'm starting the work on the front end of Bumblebee. I think one of the caliper seals has been leaking (greasy front disc, not the same side as the leaking fork leg). I'm guessing that all of the seals on the bike are now 22 years old, so about due to be replaced anyway. I've ordered 2 sets of seals & dust covers, I figured I'd do both at the same time.

The whole front end is coming off - I have a set of tapered roller bearings for the steering head, and seals to rebuild the forks. That's the next job. In parallel to this, I'm working on installinig a set of handlebars to replace the clip-ons. I may have a superbike, but I don't have a superback, so these will be very welcome. I'll figure out how to attach pics here and show the progress, separate thread. I already have a spare top yoke, it's undergoing the required mods right now. I *think* I've found a solution whereby I retain full lock and don't need to cut my beloved fairing.

But back to the anchors. One disc has become greasy (I'm guessing brake fluid), so I want to replace the seals and pads on both sides. I read through the threads on master cylinder and caliper upgrades, but to be honest, a properly working original setup will probably do all I need. At the moment, I effectively have one working disc (the other is oily), and I'm almost happy with it as is. So, same hardware, new pads.

The bike will not be going anywhere near a racetrack while I have it; it'll be getting occasional road only use. Any recommendations for which pads to choose? I would like ones that don't make too much of a mess of the front wheels with dust. Brake fade will never be an issue, so maybe softer pads will give me better braking with the stock MC & calipers, yes?

I'll be fitting stainless lines - partly because the original rubber is getting old, partly because I want to anyway, partly because the stock ones will be too short for the new bars. So I have the joys of brake bleeding to come.

Has anyone seen a good Youtube video of the rebuild process for the calipers? I'm guessing that I'll need to split them, to get the pistons out when replacing the seals.

Thanks,

ian
Ian
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IanB
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Re: Brake Pads

Post by IanB »

Oh, while still on the brakes - the master cylinder. I really don't like the separate reservoir. Talk about afterthought engineering! I saw a comment that it means the master cylinder is less likely to be damaged in a crash, but if my bike's in a position where it's going to land upside down on its handlebars, knowing teh brake handle will survive will be little comfort.

Does anyone know of a replacement unit (any make, I don't care too much) that has an integral reservoir AND the same diameter MC piston (14mm I believe)?

Thanks,

Ian
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MacV2
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Re: Brake Pads

Post by MacV2 »

Pads... SBS road... Best I have ever used...

https://www.ebay.co.uk/itm/383266817283

Yep split the callipers to service pistons & seals...

IIRC the very late Storms had square metal res pots but I'm not sure if they were integral to the levers, TBH if you've binned it bad enough to rip a res pot off then there aint gonna be much left of the front end anyway... :lol: :lol:

As for the oily disc, brake cleaner loads of it, I'd recomend you buy a 5ltr can from a motorfactors rather than the spray cans, seems to last longer rather than flashing off real quick like the cans do... Although you'll need to but a nitrile spray bottle as it eats non nitrile rubber real quick...

https://www.ebay.co.uk/itm/273776558744 ... SwyelfAKsv

This is the sort of stuff I buy but from my local Motor factors, thy may have the dispenser/spray bottle as well...

https://www.ebay.co.uk/itm/124240355367 ... Sw~7le-c6v
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IanB
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Re: Brake Pads

Post by IanB »

Thanks Mac,

I also found people recommending EBC pads, but these also look good. I checked the Ebay link. I live in Holland, postage is GBP9.42 (reasonable), Brussels then kindly slap an "import charge" on of GBP 12.61. This is basically a "we hate the UK for daring to leave the EU" tax - it doesn't get applied to anything I buy from China...

Good call on bulk brake cleaner. I do most of my cleaning and BBQ lighting using paint thinners, but I'll buy proper cleaner for the job.

Ian
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MacV2
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Re: Brake Pads

Post by MacV2 »

IanB wrote: Tue Jul 27, 2021 1:51 pm Thanks Mac,

I also found people recommending EBC pads, but these also look good. I checked the Ebay link. I live in Holland, postage is GBP9.42 (reasonable), Brussels then kindly slap an "import charge" on of GBP 12.61. This is basically a "we hate the UK for daring to leave the EU" tax - it doesn't get applied to anything I buy from China...

Good call on bulk brake cleaner. I do most of my cleaning and BBQ lighting using paint thinners, but I'll buy proper cleaner for the job.

Ian

8O NOOOO deff not on your brakes as that will KILL the seals !

As for the pads surely you can find an EU supplier ?

https://www.sbs.dk/

https://www.sbs.dk/where-to-buy
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IanB
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Re: Brake Pads

Post by IanB »

Ah, no indeed - thinners are death to rubber (and paint of course) - I just use the stuff for cleaning metal bits & pieces before painting etc.

I'll check for dealers in Holland for the pads.

Ian
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sirch345
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Re: Brake Pads

Post by sirch345 »

Ian, Mac put me onto SBS brake pads, I have to say I'm well impressed with them :thumbup:

Before removing the front brake calipers from the brake hoses, using the front brake lever if you pump the pistons out with the pads removed as far as they will go, so the pistons touch each other in the centre of the brake caliper, once the caliper is split, by holding the caliper in a vice (protected by a cloth) you can wiggle the pistons out by hand. If you don't pump the pistons out beforehand, you will most likely need a caliper piston removal tool to get them out.

Chris.
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Cadbury64
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Re: Brake Pads

Post by Cadbury64 »

VFR800's 02-12 will use 14mm integral masters, as will ST1100's (but not the ones with 3-pot calipers). My personal view is that stock VTR callipers would probably be better with a CBR600F4i 15.87mm master which would be less grabby; but I never tried that.
2017 MT-10SP, 2019 Vespa Primavera 150
IanB
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Re: Brake Pads

Post by IanB »

Thanks guys!

Chris, I had been wondering about gettingg the pistons out. I saw someone Youtube do it with compressed air, but using the lever sounds more logical; the fluid will be getting changed anyway. But just in case, I'll check to see what a caliper piston removal tool looks like.

VFR800 - yes, that looks much more like it, well done! I was planning to stay with the stock size MC piston as the general consensus seems to be that the VTR1000 has "very small" caliper pistons, hence needs higher pressure to give the required braking force. I had even been looking at getting a MC with a larger bore and sleeving it down to 14mm; the VFR800 unit will save me the trouble.

On the separate reservoir - the only real reason I can think of for it is vibration proofing. Integral reservoirs will get all of the handlebar vibration, whereas a remote reservoir mounted on a mushy rubber washer probably won't. Seeing how many bikes (including singles & twins) have integral reservoirs, I can't see that this is a problem.

Ian
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IanB
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Re: Brake Pads

Post by IanB »

I saw a listing here somewhere of caliper piston diameters of various bikes - CBR600's, 954's etc. There were 2 diameters being quoted, such as 30mm / 34mm. What does this refer to? Surely a piston is either 30mm or 34mm? They're just parallel cylinders. I don't think it can refer to the piston's inside diameter - that's just there for weight saving, and has no effect on the hydraulics.

Ian
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MacV2
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Re: Brake Pads

Post by MacV2 »

IanB wrote: Wed Jul 28, 2021 7:09 am I saw a listing here somewhere of caliper piston diameters of various bikes - CBR600's, 954's etc. There were 2 diameters being quoted, such as 30mm / 34mm. What does this refer to? Surely a piston is either 30mm or 34mm? They're just parallel cylinders. I don't think it can refer to the piston's inside diameter - that's just there for weight saving, and has no effect on the hydraulics.

Ian
viewtopic.php?f=31&t=15494

Std Storm callipers have two diffrent sized pistons in them, no idea why but the brake engineers must know.

As do the other callipers in the chart above...

I believe the the numbers quoted refer to the outer Diameter of the piston...

I use a calliper puller kit when refurbing my callipers... Cheap enough to have as usefull tool... You can get piston removal pliers but I have found them to be a bit pants... Except for doing the rear calliper as the kit doesn't have an adapter big enough...

https://www.ebay.co.uk/itm/184449992062 ... SwcUBfYcs6
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IanB
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Re: Brake Pads

Post by IanB »

Hi Mac,

It seems you're right! https://www.r3owners.net/threads/brake- ... ons.33264/

This had never occurred to me, I always thought all the cylinders would be the same diameter.

Ian
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Re: Brake Pads

Post by MK_WF »

MacV2 wrote: Wed Jul 28, 2021 8:24 am Std Storm callipers have two diffrent sized pistons in them, no idea why but the brake engineers must know.
That is related to a friction effect.
On the side where the disc runs into the pad/caliper it's creating a slight torque that drags the rear part of the pads together.
If you have equal diameter pistons the pad wear would create a slanted pad (i.e. more wear at the rear/entry side, less wear at the front/exit side)
The compensation is to apply less force at that part of the pad thus the smaller diameter at the rear.

You could see that effect even better on old fashioned 6 piston calipers.
Modern high end calipers have small single pads for each piston.
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sirch345
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Re: Brake Pads

Post by sirch345 »

Interesting info about the different pistons sizes in the calipers :)

Ian, I haven't seen a video (or made one myself) but here are a few photo's of mine when I serviced them a while ago:

Pistons pumped out so they touch in centre of caliper more or less :wink:
DSCF1256Re.jpg
The next two show brake cleaner is your friend.
DSCF1262Re.jpg
DSCF1263Re.jpg
One half of caliper (on the left) new seals, and pistons all fitted, the other half ready to fit seals and pistons.
I use red rubber grease on the seals for the pistons. Note two small joining seals in the caliper half on the right!
DSCF1252Re.jpg
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IanB
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Re: Brake Pads

Post by IanB »

Thanks Chris, those pics really help, they give me almost everything I need to know.

I think that loosening the multipoint bolts while the calipers are still on the forks might be a good idea - they are probably pretty tight, and calipers are awkward things to hold. Same goes for final torqueing up. 32Nm according to the manual.

I've ordered a used VFR800 front master cylinder, so I'll keep the 14mm MC / 27mm/30mm caliper area ratio. I did some calcs. If I compare the total area of caliper pistons to the area of the MC plunger, I get a ratio of 12.9:1. Doing the same for a CBR600F, I get 12.8:1, virtually the same. It looks like braking force on the discs for any given MC lever force should be the same. It does mean that the VTR system operates at a higher pressure though, another good reason to go for stainless hoses. Whatever, with new pads, it'll brake hard enough for me.

Ian
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